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Sentinel: cleanup around SENTINEL_INFO_VALIDITY_TIME.

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antirez 2013-11-21 16:05:41 +01:00
parent 489d889726
commit 685e79998c
1 changed files with 25 additions and 15 deletions
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40
src/sentinel.c
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@ -56,7 +56,7 @@ typedef struct sentinelAddr {
#define SRI_SENTINEL (1<<2)
#define SRI_DISCONNECTED (1<<3)
#define SRI_S_DOWN (1<<4) /* Subjectively down (no quorum). */
#define SRI_O_DOWN (1<<5) /* Objectively down (quorum reached). */
#define SRI_O_DOWN (1<<5) /* Objectively down (confirmed by others). */
#define SRI_MASTER_DOWN (1<<6) /* A Sentinel with this flag set thinks that
its master is down. */
#define SRI_FAILOVER_IN_PROGRESS (1<<7) /* Failover is in progress for
@ -68,6 +68,7 @@ typedef struct sentinelAddr {
#define SRI_FORCE_FAILOVER (1<<12) /* Force failover with master up. */
#define SRI_SCRIPT_KILL_SENT (1<<13) /* SCRIPT KILL already sent on -BUSY */
/* Note: times are in milliseconds. */
#define SENTINEL_INFO_PERIOD 10000
#define SENTINEL_PING_PERIOD 1000
#define SENTINEL_ASK_PERIOD 1000
@ -84,10 +85,6 @@ typedef struct sentinelAddr {
#define SENTINEL_MAX_PENDING_COMMANDS 100
#define SENTINEL_ELECTION_TIMEOUT 10000
/* How many milliseconds is an information valid? This applies for instance
* to the reply to SENTINEL IS-MASTER-DOWN-BY-ADDR replies. */
#define SENTINEL_INFO_VALIDITY_TIME 5000
/* Failover machine different states. */
#define SENTINEL_FAILOVER_STATE_NONE 0 /* No failover in progress. */
#define SENTINEL_FAILOVER_STATE_WAIT_START 1 /* Wait for failover_start_time*/
@ -2677,7 +2674,7 @@ void sentinelAskMasterStateToOtherSentinels(sentinelRedisInstance *master, int f
int retval;
/* If the master state from other sentinel is too old, we clear it. */
if (elapsed > SENTINEL_INFO_VALIDITY_TIME) {
if (elapsed > SENTINEL_ASK_PERIOD*5) {
ri->flags &= ~SRI_MASTER_DOWN;
sdsfree(ri->leader);
ri->leader = NULL;
@ -2915,15 +2912,26 @@ int sentinelStartFailoverIfNeeded(sentinelRedisInstance *master) {
* the following parameters:
*
* 1) None of the following conditions: S_DOWN, O_DOWN, DISCONNECTED.
* 2) last_avail_time more recent than SENTINEL_INFO_VALIDITY_TIME.
* 3) info_refresh more recent than SENTINEL_INFO_VALIDITY_TIME.
* 2) Last time the slave replied to ping no more than 5 times the PING period.
* 3) info_refresh not older than 3 times the INFO refresh period.
* 4) master_link_down_time no more than:
* (now - master->s_down_since_time) + (master->down_after_period * 10).
* Basically since the master is down from our POV, the slave reports
* to be disconnected no more than 10 times the configured down-after-period.
* This is pretty much black magic but the idea is, the master was not
* available so the slave may be lagging, but not over a certain time.
* Anyway we'll select the best slave according to replication offset.
* 5) Slave priority can't be zero, otherwise the slave is discarded.
*
* Among all the slaves matching the above conditions we select the slave
* with lower slave_priority. If priority is the same we select the slave
* with lexicographically smaller runid.
* with, in order of sorting key:
*
* - lower slave_priority.
* - bigger processed replication offset.
* - lexicographically smaller runid.
*
* Basically if runid is the same, the slave that processed more commands
* from the master is selected.
*
* The function returns the pointer to the selected slave, otherwise
* NULL if no suitable slave was found.
@ -2976,18 +2984,20 @@ sentinelRedisInstance *sentinelSelectSlave(sentinelRedisInstance *master) {
di = dictGetIterator(master->slaves);
while((de = dictNext(di)) != NULL) {
sentinelRedisInstance *slave = dictGetVal(de);
mstime_t info_validity_time = mstime()-SENTINEL_INFO_VALIDITY_TIME;
mstime_t info_validity_time;
if (slave->flags & (SRI_S_DOWN|SRI_O_DOWN|SRI_DISCONNECTED)) continue;
if (slave->last_avail_time < info_validity_time) continue;
if (mstime() - slave->last_avail_time > SENTINEL_PING_PERIOD*5) continue;
if (slave->slave_priority == 0) continue;
/* If the master is in SDOWN state we get INFO for slaves every second.
* Otherwise we get it with the usual period so we need to account for
* a larger delay. */
if ((master->flags & SRI_S_DOWN) == 0)
info_validity_time -= SENTINEL_INFO_PERIOD;
if (slave->info_refresh < info_validity_time) continue;
if (master->flags & SRI_S_DOWN)
info_validity_time = SENTINEL_PING_PERIOD*5;
else
info_validity_time = SENTINEL_INFO_PERIOD*3;
if (mstime() - slave->info_refresh > info_validity_time) continue;
if (slave->master_link_down_time > max_master_down_time) continue;
instance[instances++] = slave;
}